Question about the Shredder from TMNT 2003?

[Mada<3]

I watched tmnt 2003 a while ago and I don't really remember, even if I watch again I doubt I'll understand. So, from what I remember he's actually a small alien (which is a total turn off and kinda ruins the show) but I also remember some flashback about some ninja tribunal which he betrayed or something? that was supposed to be a lot of years ago (or not?) and he looked the same, and human, or wtf is going on actually?

 

[Hanzo]

There was two Shredders. The first Shredder was Oroku Saki he was human, he fought Leonardo I believe without his suit and died. The second Shredder was a Utrom an alien that used the Shredder outfit as a suit.
The link has info on the ninja tribunal http://tmnt.wikia.com/wiki/Ninja_Tribunal