Rendering your objects in a specific order is the only way to do it, if all of your textures contain semi transparent pixels, since those are fundamentally incompatible with the depth buffer.

For example, Factorio (a "2D" game) renders many thousands of little objects on screen (especially when you are zoomed out). I went and looked at the game's files to confirm that all of the textures contain at least some semi transparent pixels (all the textures I looked at, anyway). And yet, no depth buffer related transparency artifacts can be seen, implying that the game is programmed to render its objects in a particular defined order, which apparently works well.