They are human by definition "a bipedal primate mammal" just because they're genetically engineered doesn't change that, you can argue that they aren't natural, but they're very much human just with genetic tweaks
That humans are bipedal primate mammals doesn't mean all bipedal primate mammals are/were (or indeed will be in the future*) humans. (Though for the sake of clarity, I'm referring to homo-sapiens which is what people typically mean when they say humans.)
I'd see replicants as an (artificial) subspecies at best if not a similar but separate species. There are obvious differences as already outlined previously and they (generally) can't reproduce at all, let alone with humans. (Often whether two organisms can breed together is used as a means of classifying whether they're of the same species, in some cases a male and female of different but similar species can reproduce for one generation resulting in infertile offspring).
But again, this is the more interesting bit and more relevant to the thread than that or indeed silly semantic stuff about IVF babies.
Artificial Intelligence definition = [...] I'm literally going by the definition
No, you're cherry-picking
a definition then calling it "the" definition when there is certainly no need to limit it to computers and other definitions certainly include machines.
Replicants are designed and assembled, they are genetically engineered machines and they are intelligent, that intelligence can be enhanced (artificially, by design), it can be suppressed (artificially, by design - get rid of emotions for example) and memories can be added (artificially, by design).
I guess this is one of the hangups people have with AI too, sometimes magical thinking is applied to all things biological... but if you're really hung up on AI having to involve a computer then why doesn't the brain of a replicant count, after all, it's been constructed fully formed they don't have a childhood where it developed as they learn; the replicants brain has been engineered/programmed, it can have memories added.
*Suppose someone either speeds up evolution for Chimps or makes replicant chimps that end up being bipedal primate mammals do they become human? Ditto to any mammals.. cows for example too? If so then it seems overly broad.