For example, writing history itself can suffer a myriad of problems such as the historian's selectivity and confirmation bias.
Then, would historical sources (like oral history interviews, other kinds of testimony, etc.) suffer the same kind of problems? E.g. would it be fair to say that an oral history interview suffers selectivity because it only encapsulates a single person's perspective? Or should this be considered "subjectivity" instead? I was just having this conundrum because I was wondering if the creator of a primary source can be considered a "historian" as well, if the primary source can be considered a record of history.
Then, would historical sources (like oral history interviews, other kinds of testimony, etc.) suffer the same kind of problems? E.g. would it be fair to say that an oral history interview suffers selectivity because it only encapsulates a single person's perspective? Or should this be considered "subjectivity" instead?
In a word, yes. All source of historical information have bias, as do all historians. I might be misunderstanding you, but you seem to be implying by comparison that there are "objective" sources of historical information. This isn't really a thing. u/DanKensington has a great write up on why here, where some earlier answers are also linked.
I was wondering if the creator of a primary source can be considered a "historian" as well, if the primary source can be considered a record of history.
Again, I'm a little bit unclear on this. Could you clarify or expand on what you mean here? Historians are historians because they synthesize lots of sources to try and explain something about the bigger picture, or to explain a historical "why". Someone who creates any old document (or oral interview, or deposit in the archaeological record, etc) that gets used by a later historian usually doesn't fit this definition.