G'day luxlunae,

This matches your requirements :-)

#!/usr/bin/env perl -l

use strict;
use warnings;

my $html = '<span class="author-name" itemprop="author">Romaxton</span
+>';
my $re = qr{<[^>]+>([^<]*)<[^>]+>};

print "The idea is to reduce:\n", $html;
$html =~ s/$re/$1/;
print "to\n", $html;
[download]

Output:

The idea is to reduce:
<span class="author-name" itemprop="author">Romaxton</span>
to
Romaxton
[download]