Recognizing Palestine as a state is an act of diplomacy that certainly has no specific benefit for the people of Palestine.

But it makes incursions into Palestine by Israel explicitly of an international nature. Palestine is and has been considered occupied territory, but without recognizing Palestine as a state, what soverign country's territory is occupied?

Perhaps now that there is a recognized country whose territory is being occupied, the recognizing countries may oppose the occupation in more specific ways. Perhaps, the same sorts of protestations without specific action as in years past.

Real (positive) change for Palestinians would start with Israel withdrawing from the occupied territories[1], and that needs more than a declaration of statehood, but a declaration of statehood may be a tiny step towards that goal.

[1] It's not strictly required, but I suspect it's more likely for Israel to withdraw than it is for Israel to radically change how they interact with the occupied territories.