While I like how you describe what Paleblood is, I’m not entirely convinced that all Hunters are already injected with Paleblood from the start. If this were the case, then the opening cutscene would be our Paleblood injection, and while this may initially seem reasonable, remember that the same guy who’s doing the injection is telling us to seek Paleblood.

I also don’t think Paleblood makes you powerful in a physical sense; that seems far too grounded and regular considering they come from Great Ones, who are all so far beyond humanity’s level that practically any human will suffer immense consequences from any sort of contact, from falling to the plague of beasts to actual post-birth stillbirthing.

I think that, for this argument to apply, the power that Paleblood gives is on a much more esoteric and mental level, and that instead of making hunters all beefy, they instead bring your ‘Insight’ to a level that matches the Great Ones, effectively making you a Great One by default.

For a prime example, let’s look Rom, who we know for a fact was once human, and know from the achievement that she’s now a Great One. Rom is not physically strong. She can barely move her fat, ugly body, and does practically nothing physically during her entire fight. Yet she is a Great One nonetheless. This is because, through Kos, she has been granted her metaphorical (and likely literal) eyes on the inside, and can hold the eldritch knowledge of the Cosmos while maintaining her barrier over these eldritch truths.

Similarly, after defeating the Moon Presence, one would presume that finally ascending to a Great One would make one extremely menacing and powerful, but we end up transforming into a helpless little slug.

Ascension to Bloodborne’s version of godhood has nothing to do with power as we understand it, and that’s entirely intentional, given the way Great Ones are described as largely incomprehensible to the average person.