My mother tongue is Portuguese, and we have two verbs that can be translated as “to be”: Ser and Estar. I Wonder if English has ever had this feature?
I don’t know enough about Portuguese to understand the subtitles of Ser and Estar that would be needed to answer this authoritatively, however, I can talk about old English.
Old English (Anglo-Saxon) had a distinctly more complex verb to be than modern English. The variation that you describe between ser and estar is referred to as case. Most Modern English verbs have taken on a simplified grammar for cases, however, Modern English has retained a little bit of complexity in to be that other verbs don’t show. For to be the list of cases is: be, am, is, are, was, were, been, and being. To understand how it used to be, I suggest that you look at the table of forms of to be at Old English grammar on Wikipedia.