Question

Then at the bottom was the biggest line of all, which said:

LADIES AND CHILDREN NOT ADMITTED.

"There," says he, "if that line don't fetch them, I don't know Arkansaw!"

Twain is most likely using humor to convey his viewpoint that

Answer 1

From those lines, twain is most likely using humor to convey his viewpoint that People are often tempted by the thrill of something naughty.

It's really emphasized by the words "Ladies and children not admitted", that will arouse a lot of interest