So the problem here is taht no where did you manage to get HTML code to actually render.
You’ve tried a number of plugins to no avail.
The problem here is that you are using a wordpress.com blog that doesn’t support doing what you are trying to do.
This is a Wordpress Problem.
You got it working using a shortcode plugin so use that. Thats likely the only solution to wordpress.com hosted blogs due to it’s limitations