I have included a picture of the screenshot from the trailer to prove that that person is the young Boba Fett:
Why do I believe its boba Fett:
1: Both the select picture and the screenshot have a zipper in the same place, not only that but the same style vest,Dark blue clothes with a light coloured vest over the top of it,seen in the 3 pictures on the right.
2. The eyebrow is basicly the same in both end pictures
3. Both the skirt and belt are in the same place indicated where indicated
4. In the cartoon picture we can see the back of Bobas head,he is of course wearing a helmet which you can see 2 lumps on both sides and the top which of coarse is the same as the screenshot picture from the trailer.
If this doesn't prove that its Boba Fett I don't know what will!!!