Hints are in black under each level

Level 1

whos in the image?

Level 2

error page

Level 3

certain numerals

Level 4

KATE

Level 5

different web pages, one of them is scratch

Level 6

Win95

Level 7

what came before oreos?

Level 8

numbers to letters for the second part

Level 9

computer logic gate

Level 10

chemicals! biology class!