Why should I create a paragraph if I can just type the whole text between <h1> </h1> for example?

Hello I just started on codecademy and I have a question:

Why should I create a paragraph

if I can just type the whole text between

for example? I understand that

gives you big letters but the question is what does the paragraph add? If someone could help me that would be great.

UI and UX (user interface and user experience) are important factors, having everything in such a big font is not a pleasant user experience

furthermore, headings are relevant for search engine:

https://www.rankwatch.com/learning/content/are-your-headings-optimized-search-engines-and-users

this is important, google values this when ranking search results. You want your website to be found by google (and other search engines)