But if observation is subjective because you are interpreting, then interpreting must be.
Must be
what?
I merely said that we cannot observe something without also simultaneously interpreting it. I never said, or insinuated, that you can interpret something without observing it.
Being a human inherently has a limit set, and that limit is only known to non-humans. If we are unable to know or do not know our innate bias, are we subjective?
This question is confusing, but there's no such thing as objectivity within a set of observational limits that precludes the external. There's no "human objectivity," since what designates the category of "human" can only be presupposed from within, never verified from without - and that is emphatically not an objective set of criteria. So we can only ever be subjective, from our respective, individual viewpoints.
This leads to my next point:
But you ignored the analogy which I think demonstrates a difference between observing and interpretation.
To be able to say "humans have thumbs" necessitates making a categorical claim about the entity in question - in this case, a human. When you say "humans have thumbs," you've already made an interpretive claim that the thing you're talking that has thumbs is, in fact, a human.
Now, you might say that this is one of the biological or physiological criteria for calling something a human: that it has opposable thumbs. But if this is the case, then you must see that you've also made an interpretive claim in order to qualify the thing you're talking about as "human."
In other words, to be able to say "Humans have thumbs," you have to have done one of the following:
Say "This thing has opposable thumbs. It must be a human!" (an interpretive observation)
or,
Say "This thing is a human. It must have opposable thumbs!" (an interpretive observation)
(of course, I'm simplifying here - other animals do have appendages like opposable thumbs)
Now, let's suggest one final possibility: get rid of "the human" altogether, and make the following observation: "This is a thumb."
Ignoring the "this," let's assume you're making a very basic observation that some object before you is a thumb (it doesn't even have to be opposable). In order to make this claim, you're drawing on a history of knowledge preceding that allows you to say "This is a thumb." You're making an interpretation, albeit a very fast one, that the shape/figure/form/etc. that you're observing is, in fact, a thumb. Interpretation is built into this observation, whether you realize it or not.
A more accurate conception of science is, as Dak suggests, that it's "inter-subjective." It consists of competing perspectives that are constantly being tested and occasionally reproduced. Anything that claims "objectivity" is, in my book, trying to pull the veil over your eyes