RewriteRule that accommodates numbers and words

My knowledge is limited on the subject but I will try and look forward to being corrected by some knowledgeable members.

### command to implement RewriteCondition AND RewriteRule
    RewriteEngine on

### reads command line and interprets as a file
    RewriteCond %{REQUEST_FILENAME} !-f  
        
### reads command line and interprets as a directory
    RewriteCond %{REQUEST_FILENAME} !-d

### interpret, execute and route RewriteCond to specific root file including directories
    RewriteRule ^(.*)$ index.php/$1 [L]

### interpret, execute and route RewriteCond to specific root file excluding directories
    RewriteRule ^(.+)$ index.php?sponsorUsername=$1 [L]