how to increment all file names in a folder

[SoulsKeeper]

are the file names just numbers like "12345678" or do they partly have numbers like "data2018"?

All the files in the folder got the exact same name which is a pain to work with, there are thousands of them so I probably need to use a loop right?

I need it to automatically go from file to file and add a number to each of them like so:
file.

file1.

file2.

and so on...