If I understand it, when in SHARES the same number or more than the current difficulty appears, I would have 1 chance of finding a block, is that correct?
No, you chances are the same with every share, you never get "closer" by doing more shares. If your shares = the current difficulty, your overall chance of finding a block works out to approximately 63%.
And the SHARES monero increases with each valid action of the miners, right?
No idea what shitcoins have anything to do with this here.
with two s19j of 104 th, would you try your luck??, if so, how long would you do it?