Do you think this a long walk home?

About three miles? It's a good size walk and, like you said, good for you. :)

I used to walk about 30 min home, from the nearest city bus stop when I was in college.

sounds like a colossal waste of time. You could be building houses or harvesting crops instead.

As I assume, it takes 50 minute to walk from school to home without bus. To me it would be long walk indeed, but hey...as long as you enjoy it.

Fairly long, but nothing ridiculous. Sounds nice to me.

It's not long time wise. As long as the route is safe nothing wrong with it.

Yes it is.
It's also dangerous.
Someone can learn your route. Traffic. Dehydration etc.

If you want to walk, walk in a park or in your neighborhood close by letting your parents know....and walk with someone....even though some people can overpower two children....
It happened here but the two little girls were 4 and 6.

Also did you let your parent know this? Did you tell the school and the bus driver? Because if something happens to you the school/ bus driver can get in trouble....