Quote:The novels all dealt with this. It was The Doctor playing a trick on the Master. He was never half-human
The novels aren't canon.
Besides which, The Timeless Children has thrown everything up in the air. People are assuming that the child is a completely alien being, but for all we know perpetual regeneration is discovered on Earth in the far future, on on some alien world that human colonists have reached.
Chibs might even be going (God help us) for some kind of time paradox nonsense. Something like: The Doctor IS a Gallifreyan or Gallifreyan/Human hybrid born in the far future, the first such born with natural perpetual regenerative abilities, but was sent back through time so that Gallifrey could have regeneration in the past.
Doctor Who has no canon
Chibnall I doubt is going to overcomplicate matters. That's what the novels and audios are for, which you can ignore to your hearts content since you're one of 'those fans' that only think the television counts. All he did was give the franchise's expanded aspects some variety with the timeless children twist.
Everyone's ''lord and saviour'' Russel T. Davies even came out last year and said he reckons 'every story is true'