Speak of Doctor Who: Gallifreyans/Time Lords are humans.
To start with the obvious, Time Lords are externally indistinguishable from Earth humans. But there’s more.
In the Fox Doctor Who TV movie, The Doctor says he’s half-human. Even though it was Fox, that Doctor has now been firmly established in the continuity of the BBC series. We all know that The Doctor lies, but it would be really out of character for him to lie just to get into a companion’s pants, so there must be something to that statement.
The Doctor’s Daughter, created by space magic cloning technology, apparently really is half-human. So Time Lord and human DNA are apparently compatible. Which, sure, space magic, and space opera conventions, but it’s still…interesting.
River Song has Time Lord DNA. She’s of entirely human descent, but she was conceived while in the Time Vortex. So, humans conceived in the Time Vortex gain Time Lord DNA. This, to me, is the clincher.
Also, at the End of Universe, the human species is splitting into subspecies. Some humans (or at least a Time Lord in disguise as a human) are trying to create technology to escape the heat death of the universe. We know that humans gain access to, although not master of, time travel by the 51st Century, looong before then.
So, a group of humans escapes the heat death at the End of the Universe by time travelling back to the Big Bang, in a colony ship. Children conceived during this transition are exposed in utero to the energies of both the Time Vortex and the Big Bang. The result: Time Lords.
This explains a lot about The Doctor, as well. He has no use for authority, and boundless curiosity. We know that he’s peered into the Time Vortex and seen…something.
Time Lords are forbidden from viewing or travelling to their own history, either their personal history or the history of their people (I don’t know if I’m making that part up or if that’s something I half-remember from the show). The Doctor doesn’t care about the rules, so he looks into the Time Vortex and sees the truth - Time Lords are actually far-future-deep-time-shifted humans, the descendants of Home Sapiens of Earth.
With this knowledge, that he’s “half-human”, he becomes inordinately fascinated by his distant ancestors. He constantly observes them, interacts with their history, takes them as companions, tries to help them, tries to guide them away from the worst aspects of the Time Lords without creating paradoxes that will erase the Time Lords - and The Doctor - from the time stream.
He knows what we humans will eventually become, so he always hopes, and expects, us to be better than we often are, and it’s always a bitter disappointment to him when we don’t live up to his expectations.