Yes, "Daaad, Zeus the Greek god ate my homework!" isn't strong evidence, certainly.

But the way it points (in relation to P(Zeus exists)) is clear.

I don't think it is. If Zeus really had eaten the homework, I wouldn't expect it to be reported in those terms. Some stories are evidence against their own truth -- if the truth were as the story says, that story would not have been told, or not in that way. (Fictionally, there's a Father Brown story hinging on that.)

And even if it theoretically pointed in the right direction, it is so weak as to be worthless. To say, "ah, but P(A|B)>P(A)!" is not to any practical point. It is like saying that a white wall is evidence for all crows being black. A white wall is also evidence, in that sense, for all crows being magenta, for the moon being made of green cheese, for every sparrow falling being observed by God, and for no sparrow falling being observed by God. Calling this "evidence" is like picking up from the sidewalk, not even pennies, but bottle tops.