I’m no expert here, but you may want to check in to what the word meant to the author who wrote it.
Try here:
biblesuite.com/hebrew/5397.htm
You have to remember, up until perhaps the last few centuries BC, the notion of a soul as we conceive of it wasn’t really abound in Jewish theology. Soul and life were interchangeable, and I really really don’t think that if you read “soul” from an OT book, you ought to be comparing it with “soul” in the modern sense of the word, or how we Christians interpret it.
Again, you need to check with someone more expert than me, but from what I recall of Bible study, OT “soul” is just another equivalent for breath, or life-- the gift from God that brought unliving clay to life. To take away your breath, your soul, or your life, would all mean the same thing. Therefore such a passage as you find in Ezekiel would have absolutely no bearing on the concept of souls that wasn’t developed into Abrahamic religions until much after Ezekiel lived.
Furthermore, let’s not forget that Jesus calls God the God of the living, and rebukes the Sadducees who didn’t believe in resurrection (they only held the Torah to be authoritative iirc), an idea that, again, was not developed until late in OT history (probably around the advent of Hellenism, just a guess). And when Jesus tells the penitent thief he will be with him today in paradise.
Admittedly that in itself is not a testament to immortal souls, but it diminishes the importance of the quote from Ecclesiastes.
And it’s not like these quotes prove anything. There’s also probably one hundred quotes that say God will requite the wicked and uphold the just in life, yet the authors of Ecc, Job, and others clearly knew that this was not the case (as do we!). You can’t pull quotes out of no where without looking at their contexts, who wrote them, why they were written, what time, etc…