The 115 gr and 124 gr weights are historic legacies. 9mm ammo specs in europe frequently established a required weight range, energy minimum and pressure maximum and left the details up to the ammo companies. As previously noted, those weights were in grams and the resulting English system weights derived from those. Cartidges of the World (book) or Wikipedia will probably tell you more than you want to know, with Wiki being a wee bit suspect. You also have to recall that 102 years ago, the selection of available powders was limited and this affected the weights of bullets that could reasonably be used at acceptable pressures.

The 147 gr load is the result of much more recent work to develop sub-sonic rounds for use in suppressed submachine guns for special operations work. Figure the 1970-1980 time frame. I believe it's also adapted to pistol operation as some of the original stuff was unacceptably anemic in handguns.

As noted earlier, books have been written on this subject. Check your local library or bookstore.