I would use two examples Yoruba and music.
There are two Yoruba dialects Akoko Edo and Ikale that are so unintelligible to the average Oyo Yoruba that following your argument these two dialects should be seen as separate languages from Yoruba. No Yoruba person will consider them anything other than Yoruba.
Directly now to pidgin. Before I arrived in the UK and shortly after I could not understand a word of Jamaican patois as indeed most Nigerians today would not. Over the years it became clear that the building blicks were English (ywisted beyond recognition in many instances. To the extent that these originating blocks are English and not French it temains an English 'pidgin' dialect e.g 'wha ya ta bou?' what are you talking about?
''who ya deal with?' Who do you think you are dealing with? 'Wha a guan?' What is going in?'
Your reference to latin is entirely different. A whole transformation spanning hundreds of years means the Romance languages ( from my experience of taking spanish in graduate school)are similar to each other than to latin. Hausa and Yoruba were going in a similar direction with the exchange of loan words before the intervention of English as lingua franca. It is that trajectory that I want resuscitated with my passion for indigenous multilingualism.
Still on Jamaican patois as a dialect of English. Almost every successful female singer in the fruitful harvest of music that 2016 was wanted to duet with Sean Paul the consummate patois singer. His rich timbre and patois dialect is sought after because the singers accept his patois as a refreshing dialect juxtaposed with their normal dialect. This perhaps proves Roland Barthes right in comparative musicology that in music the 'grain of voice' sets apart the true masters from the others.
Sent from my Samsung Galaxy smartphone.