The idea language fundamentally shapes thought, is called Linguistic Relativity. Formally it has been called the Sapir-Wharf hypothesis, but for various reasons it's not a good name (like them not stating a clear hypothesis, and them not having worked together, and most importantly that far more general issues are considered under the topic than in their work).
A distinction is made between strong and weak linguistic relativity. The strong version says, if a language doesn't have a word, the thought that goes with it should be impossible. Orwell's fictional language Newspeak from his book 1984 explores the idea of strong linguistic relativity, or determinism of thought by available words. Fortunately, there is basically no evidence for this strong form. I would look to Hofstadter's book Surfaces and Essences: Analogy as the Fuel and Fire of Thinking for why: words don't exist as isolated tokens, they are meshed in what Wittgenstein called modes of life. He said:
"In this sort of predicament, always ask yourself: How did we learn
the meaning of this word ("good", for instance)? From what sort of
examples? In what language-games? Then it will be easier for you to
see that the word must have a family of meanings.” ― Ludwig
Wittgenstein, Philosophical Investigations
The weak form of linguistic relativity, is basically unarguable and has plenty of evidence: that language influences how we think. For instance The way you see colour depends on what language you speak. I would interpret the weak form of linguistic relativity in terms of organising experiences into salience landscapes.
Solitary animals like octopuses and bears, are clearly capable of solving problems, implying they can make efficient abstractions - thoughts. We know octopuses in particular just don't interact enough to have language, so in many ways the complexity of their minds is a puzzle. They lost the shells their nautilus relatives kept, long before the rise of mammals or birds, so it's thought the adaptive arms-race may have been key, plus their complex genetics. They have an amazing ability to predict how to manipulate predators and prey, in ways that we can watch them learn and hone in their short lives. Their wrapping themselves in loose shells to defend from sharks is probably the most advanced tool-use we know of outside of the mammals. So, it seems their intelligence is linked to 'seeing into' the minds of predators and prey, and this links to their heightened 'seeing into' objects. We call this intersubjectivity. And it seems to be more fundamental to complex thought, than language. We can look at language as a method of amplifying and networking intersubjectivity. Discussed here: According to the major theories of concepts, where do meanings come from? I would then describe language as essential to complex concepts, ones that go beyond the capacity of one mind, or one lifetime.
I would argue the key distinction with knowledge, is from information. Information is just a record of data, sensations, etc. Knowledge situates us in relation to the information. Discussed here: Does knowledge require consciousness? In this sense thought and knowledge are possible without language, like the octopus situates itself.
You say:
word that for 'something that knows only of its own existence'. If
such a something exists it would have to be 'God' because it would
have to account for all existence that it experiences as being itself,
and that is generally how a theistic God is defined.
I don't agree with any of that. What reference do you have for god being defined like that? The precise details of whether god is outside Creation, the nature of omniscience or the limits of god's knowledge, have been extremely important to theists and the causes of schisms. Bandying about loose definitions pulled from the air, is just no way to have a productive discussion.
What you describe, "something that knows only of its own existence", is exactly Descartes' source of fundamental certainty: 'Cogito ergo sum'. Which absolutely does not define a deity.
