I hope my response is not too off base to the OP, but I did have some minor discussions with friends and a brother about the phrase 'I think, therefore I am'- though this post is not really concerned with Descartes nor the Meditations.
What the statement claims to be is a causal claim because of the word 'therefore'. However, the claim lacks a causal necessity, nevermind that Descartes came across that sequence. The claim in no different than the claim "I think, and I am".
This reordering shows us what the claim actually is, namely, it is not a causal claim but grouping of the imaginary (think) and the metaphysical (am, being). Algebra shows the two "I" claims to cancel; afterall, "I, therefore I" is superfluous.
Then we have something like 'thought begets existence' or 'thought = existence'.
What constitutes thought and what constitutes existence? I am fairly confident that if you asked enough questions from people you would find they do not agree upon what things are capable of thought- and 'existence' is also in uncertain waters even among logicians.
I rather like the simplicity and consistency in "I am here".