.htaccess: RewriteRule not Working using just the value - php

Question

I've done a lot of research to solve this problem but I still can't figure out why it won't work. Initially I had Re-written my urls to add a .html but I want to change that and keep them simple without any suffix.
Here's an example of original link
http://www.howwe.biz/artist?a=eddy-kenzo
I used the rule below to change the link above and add a suffix .html
RewriteRule ^([^/]*)\.html$ /artist?a=$1 [L]
The result is : http://www.howwe.biz/eddy-kenzo.html
I want to rewrite the original link to something like this
http://www.howwe.biz/eddy-kenzo
I've tried using RewriteRule ^([^/]*)$ /artist?a=$1 [L] to achieve that but I get a horrible server error
Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, webmaster#howwe.biz and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log. Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.`
The eddy-kenzo in the url is the value. What's odd is that if I add the name which in this case is a, it works. See below:
RewriteRule ^a/([^/]*)$ /artist?a=$1 [L] is valid for http://www.howwe.biz/a/bebe-cool but I need this like this http://www.howwe.biz/bebe-cool
What is it that am doing wrong. Your help will be much appreciated.
Sorry if this was tl;dr.

Answer 1

This should work :
RewriteEngine on
#1redirect "/artist?a=foo" to "/foo"
RewriteCond %{THE_REQUEST} /artist\?a=([^\s]+) [NC]
RewriteRule ^ /%1? [NC,L,R]
#skip the rule if the request is for dir
RewriteCond %{REQUEST_FILENAME} !-d
#skip the rule if the request is for file
RewriteCond %{REQUEST_FILENAME} !-f
#rewrite anyother request to "/artist?a="
RewriteRule ^([^/]+)/?$ /artist?a=$1 [NC,L]
Your rule
RewriteRule ^([^/]*)$ /artist?a=$1 [L] failed because it is rewriting any request to target url unconditionally , the target url matches the pattern and it rewrites to itself. You rule will work with the following conditions:
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^/]*)$ /artist?a=$1 [L]

Answer 2

Try this:
RewriteRule \/(.*)? /artist?a=$1
It takes everything from behind the last / to the end, and adds it to $1.