It is a thinking problem that we have to deal with. Your hint that I answered the question myself and how you put it into words raises new questions in principle.

so if things change and are different each time, they are always new.

If something existing becomes something new, then the question arises at what point exactly (in a period of time / or space-time) such a transition - from the existing old into a new - happens, doesn't it? When an egg cell and sperm cell fuse together, are they something completely new? Or are they a combination of something existing with something new - or better: something different?

Things live by renewing themselves, they are in part totally the same, in a part that may not have changed, and in part totally different, in a part that has changed.

Which part remains the same, which part changes and contains the old and the new equally, and which part is completely new? In principle, this cannot really be said, because you cannot separate parts that remain the same, parts that have changed slightly and completely new parts, because they always form a whole, I think. It would make no sense at all for the growth process to make a separation, because this would interrupt the growth and thus destroy it.

The transition from a cell cluster into a foetus into an embryo cannot be considered as separated from each other, because after all the cells are still present from which the living being grows. However, it can also be said that these primordial cells are subject to change and through growth and ever new connections to the end of a baby's growth in the womb may no longer be completely identical with their own initial stage.

Actually the term "novelty" is misleading and one would have to say "otherness", which in turn is linguistically connoted quite differently.
For example, if the virologist says "I have identified a different virus", it would sound less dramatic (or scary) than if he says "I have discovered a completely new virus!

"New" suggests something unknown. Something that we don't know suggests that we don't know how to deal with it. It suggests that this newness does not allow old familiar considerations, is not accessible to common treatments and methods.

My thesis is: Since we can't really know, spreading the news that we have discovered something new is rather questionable and should make us skeptical. We really can't know when something old has turned into something new, because we never really know the point where this transition actually takes place, nor do we know the exact time period, i.e. the exact duration of the change process. All we can do is to artificially create this interface and say: That's what we suspect here and that's why we make a cut here. Then we define the point in time. So we cannot speak of knowledge, but only of consensus and agreement in our considerations.

I agree on all points with you considering "death".