Man made (aka human made) is obviously anything made by a human. So let's rather talk about natural vs. artificial.

Here, the concept probably boils to the idea that humans have a consciousness, and a free will, which are not part of nature, but something special. It's kinda religious.

But artificial could also have a more generic meaning of something extraneous doing things in an ecosystem, and changing it in completely new ways.

It's like in a game where the players are controlled by users. The users are not part of the game and can create things that would never come to existence by means of the game's nature, i.e. via procedural world generation or NPC AIs. So e.g. villages in minecraft are natural, but user-built structures are artificial.

Note though that goods produced by nature are not strictly better than artificially created goods. To name two examples: (1) Carrots harvested from a generated village in minecraft are no different from player-planted carrots. (2) Medicine is not better just because it's extracted from plants.