Weird that Metallica's debut album, as an example of early thrash, has quite a lot of dissimilar elements to Motörhead. There are also obvious differences in the debut albums of Slayer, Megadeth, Exodus, Anthrax and Overkill as examples of other early thrash metal. It's quite obvious that Motörhead is far from the singular catalyst to start thrash metal.
Some other bands that are clearly not solely inspired by Motörhead but definitely influenced early thrash bands according to the bands themselves are Judas Priest, Iron Maiden, Queen, Blitzkrieg and Tygers of Pan Tang, just to name a few. Elements of all of those bands can be found in actual thrash metal bands.
You're not living in reality if you think that Motörhead was thrash metal or was singularly responsible for invented the genre as you have claimed.