I understand that for a new bitcoin to be born it is necessary to solve a SHA-256 problem, that is, to make a machine effort for this (a real race). Whoever makes this effort first takes the bitcoin, the rest are left with nothing.
My big question is why this machine effort is necessary to solve the SHA-256 problem? what do the masterminds behind bitcoin do with the SHA-256 solution? I don't really understand this, I may be making a mistake about it.