It’s accurate to claim that “the perspective of everyone partakes of a uniquely subjective character”, but not that “everyone is biased.” The semantic differences are subtle. But also crucial.
1) The first statement is an acknowledgement of the profoundly unique location of the nexus of awareness: no one else is looking through your own eyes but yourself; your memories and recollections are always derived from your uniquely encoded set of first-person experiential impressions, sequentially accrued over the passage of time but accessed only incompletely and hence always to some extent with less than perfect accuracy. The time-binding faculty of human minds is innately imprecise, it’s a potential that varies—some individuals have memory abilities that are uncanny, but they still don’t store every impression registered as a fresh experience. That’s the main reason written language was developed—as a means of storing and preserving significant details as a stable textual accounting that can be decoded—received and understood—by those with the ability to read them with comprehension and share that witness in common. But there’s always a difference of perspective between a journaler reading their own diary and the same text as read by anyone else. Just as there’s always an element of parallax in perspective—”point of view”, or “field of view”—between any two given people, even when they’re sharing the same circumstance, in the same room, around the same campfire. So there’s no getting away from the reality that no single human being possesses an “objective perspective.” Even the shared perspective of an intimate group observing the same set of near-field external phenomena doesn’t qualify as “objective”. The presence of multiple witnesses can potentially supply some amount of additional verifiability in that regard. Humans providing honest accounting of an experience typically share a lot of overlap in the details they register perceptually and interpret cognitively, and sufficient overlap exists to demonstrate that the human bandwidth is drawing on a commonly agreed basis of incontrovertible facts. That’s what constitutes “objective reality”, for all practical purposes. There’s a common foundation of agreed perceptions and a shared gestalt of phenomenal impressions. But every individual views that shared reality from a slightly different locus, and the details of those impressions, those stimuli, are registered slightly differently by each observer-participant. That’s what it means to say that “the perspective of everyone partakes of a uniquely subjective character.” Or, in shorthand form, “everyone’s reality is ultimately subjective.” That statement should not be misinterpreted as if all human awarenesses reside in their own separate dream worlds, or are capable of constructing their own phenomenal existence on an arbitrary basis, to their own personal whims. The statement “you create your own reality” is catchy, but terribly misleading. It’s much more beneficial to reframe that assertion into “you have some crucial latitude to influence the course of your experienced reality with your own moves.” Both within the internal “mental set” reality, as interpretive framing, and in the external “phenomenal setting reality”, with decisive actions. That’s my take, anyway: even given the cascades of interrelated changes that delimit and to a large extent exercise a predetermined power over the path of existence of every human being, under the terms that define what’s generally acknowledged as human self-aware consciousness, individuals retain some latitude to exercise free will and agency over their own decisions.
2) The claim that “everyone is biased” sounds as if it’s similar to, or derivative of, a conclusion about the innate subjectivity of human existence. But upon closer examination of the sense in which the assertion is most often made, it’s a much simpler declaration, simultaneously superficial and generalizing. The statement that “everyone is biased” is most often posited as a truism for the purpose of closing a discussion, implying a profundity and irrefutability that it doesn’t deserve. Asserting that “everyone is biased” isn’t intended to convey a reference to the universal human condition, in the context of a political discussion. In that circumstance, if given close reading, “everyone is biased” takes on the character of a linguistic Turf Claim. The chain of fallacious reasoning follows this line: 1) that since omniscience is unattainable by humans, subjective Bias is ineradicable; 2) that in the absence of perfect objectivity, the goal of Impartiality exists only as an ideal that isn’t worth pursuing, 3) that the existence of any Bias per se is inherently disqualifying, and 4) therefore not to being compared and judged in terms of relative strength of logical reasoning and factual support offered in support for an argument; ergo 5) because “everyone is biased”, no position can be held to be more valid than any other.
That’s why it’s the overwhelming case that the only side who ever offers the observation that “everyone is biased” in the course of making a political argument is the one that’s losing. They’re seeking assent to that proposition as a Truism, lest anyone in the audience notice that they’re getting their ass kicked by the facts and logic provided by their opponents.
https://duckduckgo.com/?t=ffab&q=logical+fallacy+list&ia=web
Learn the fallacies found on the lists in the sites of those search results--they're all similar, some are more detailed but they're basically the same. (Note: if there was no such thing as objective truth, the lists would argue with each other. They don't. They're in pretty much unanimous agreement. People might be subjectively biased, but the rules are not.) There are occasionally some fine points to sort out, but it's mostly about practicing a set of rules that might possibly run to ten printed pages. The 15 most common logical fallacies can be summarized on one page.
It's the weirdest thing; learning how to think clearly and argue logically and ethically from finding out what it looks like when it's done wrong.
Learn the fallacies, and you're halfway to having logical thinking skills. You only get the other half when you apply your knowledge to cleaning up your own arguments.