The explicit theology matters less than how it’s taken. The Catholic Church had a lot of debates and grumbling about the veneration of saints and whether or not it was being taken too far into the realm of worship. The Saint tradition partly resembled Hellenistic hero cults but also always gave me a vibe similar to village gods. Not seen as powerful as major pantheon deities but more approachable and able to serve as intermediaries to higher powers. The line between spirit and god is very vague when it comes to village deities and hero cults. Not theologically but from the perspective of the practitioners themselves.
Depends on the context of the question.
If we only care about what common people practice, then maybe.
But if we do that, we can run into problems, as this include apostasies, personal misunderstandings, etc., the misunderstanding being the most problematic as they often don't make sense when reintegrated into the beliefs as a whole.
And for this specifically, it's not like Catholicism doesn't have an independent & coherent explanation for the devotion to the saints that doesn't even relate at all to earlier polytheisms.
The Saint tradition was never going to evolve into anything polytheistic within Catholicism itself but I certainly could see it evolving into a pantheistic Christianity in say Mesoamerica had Spanish rule been interrupted in a very specific and unlikely way. A lot of the early and intermediary forms of Catholicism tend to resemble a polytheistic Christianity as a result of the Saint tradition being used to syncretise and incorporate local faiths and therefore encourage conversions. Though how one would halt the Christianisation of Mesoamerica partway through it occurring I’m not too sure.
Santa Muerte & the Day of the Dead are basically this in OTL. And you could look how the Church tried to control those practices.
Judaism into Christianity? Trinity and so on. Am I very wrong?
Not in context (at least for most sects), all three members of the Trinity are still part of the same divine being.
Very Oversimplified! Claiming that the Trinity are different gods is similar to claiming that I am three beings because I have an
id,
ego, &
super-ego. (I'm not comparing these to the Trinity itself, just the similarity of having three parts in one.)
[Added] Both of this are basically a similar issue to calling Buddhism a religion.