the leader of Team 7

Kakashi is the leader of Team 7, teaching them about the concept of teamwork and support for one another.

one of the significant characters in Naruto

Since kakashi is one of the significant characters in Naruto and has multiple likable traits, his fan base in the anime community is far from unreasonable and unexplainable.

a very powerful and experienced shinobi with advanced proficiency

Kakashi is a very powerful and experienced shinobi with advanced proficiency in countless areas including mastery of all three main ninja skills.

Hokage

Kakashi is/was Hokage for a while and Naruto was a prodigy.