is there a way to send subscribers data to my list via the HTTP POST request to the certain URL
or anyway to embed the form in HTML / provide a static form code, without a script?
Yes. Search the Community for "lead capture/save" and you'll see discussions of how people post to the forms endpoint. In fact if you add a form element to a Marketo LP (not the embed of course, but a named form element) and then view-source, there's always a <noscript> form that uses this endpoint.