Yes gotcha.

I very much believe that it is what you call an "evolutionary accident". I wouldn’t probably call it accident, but rather like one of the possible evolutionary branches of life forms if you know what i mean. (The outcome though regardless of the definition is still the same).

What would make you think that our sentience is actually rising that much? Sure we have plenty of new technology, we have bested (most probably) all of the other life forms on Earth, but the vast majority of the world still lives in "medieval ages". From my perspective humanity is still in its prenatal stage (and will probably destroy itself before it ever manages to climb out from that stage). Thus said thinking that from the perspective of Truth/Reality we can’t possibly know whether we have even matched the "average sentience" of all the living species, let alone proclaim that we have reached a state worthy of recognition, or possibly a state that "all sentient beings are bound to seek at one point". Maybe we are well below average of "sentience" and that is why we are reaching those conclusions?

Overall you added some great points. But then again the argumentation of the "rising sentience" you have shared is still based on a premise that this is the only way where life forms can lead (based on our very limited understanding of the world a life itself). We have no idea how other life forms think or act. All we can do is to assume that life forms based on CO2 (did I say it right?:D No chemist here:D) will always do what humans incline to do. As you very well pointed out

We don't have enough data...

We can only assume and I was raised in a philosophical communities that were sceptic in its nature.