Well I think it should be pretty clear to everyone who holds that man evolved from apes that

it is possible or at least theoretically possible, to pruduce hybrids of humans

(it might just so happen that no animal close enough to us exists, but that doesn't mean it was not possible that there could have been).

What that goes to show ethically really depends on our notion of human rights and how to deal with vague terms. The creation of a hybrid would pretty much establish "human" as a vague term since you get things of which their humanity can be reasonably disputed.

It would not show that we ARE animals but that we are at least continuous with animals.

We might judge that animals close to our level of intelligence are deserving of some rights, for example.

We might, however, say that actually our notion of "human rights" we apply to all humans out of convenience, not out of genuine reason. In other words, some humans might not actually deserve all the rights we give them but because epistemically, we cannot tell which ones, we grant rights to everyone to ensure that we behave well within the bounds of ethics. Anything that is not entirely human, however, would not come within that protective sphere of rights.