Eehhhh? Isn't people with titan's power just can life for 13 years after he get the power

Yes? So I don't understand why you're so confused?

Titan armor still alive? He appeared when eren still a child right, and then 5 years later his identity revealed, so why he is still alive when he become old?

Maybe he was someone else at the time? I doubt Reiner was fighting like that at 10 years old but it's possible..

As other posters have said, the current (not present) timeline has the young Titans fighting to decide who is the next Armoured Titan. So, if that's the case, why isn't it possible that Reiner had that power transferred to himself from the Armoured Titan that appeared when Eren was still a child?

My point exactly. I doubt Reiner was the one in control of the armoured Titan at that time.

Hmm but. In the manga reiner said to eren that he was the one who become armored titan when he was a child, right?

yeah but it's only been 9 years since then (Zeke said it). that leaves him 4 years, either in the past (before the breach of Shiganshina District) and now (chapter 91-92)

Sorry, I mean Magath (not Zeke) who said it

Ohh i see isee.. thanks for your information ^^