It seems too me that these days there are so many genres to choose from, some seem to be sub-genres of others. Take ska for example; it originated in Jamaica in the late 1950's so does that make ska punk a descendant of ska or punk? Its just all confusing and i guess it all has to do with the evolution of music, but where do the sub-genres begin and the main ones end? what exactly are the "Father genres", the ones that all subs descend from?
does anybody get what im asking?

Only a bunch of elitists and historians care about taxonomy in so much detail.

Most of modern music is derivated from Blues.

The subgenres can help describe the style or roots of a band; some are made-up genres by smug pseudo-artists (comparable to those Contemporary Art movements bullshit) though, or as the opposite force by derision (as often seen on underground rock clubs flyers).

They are not to be taken as an absolutes; a lot of bands don't actually the many labels applied to them, either because they don't identify to it, or because the labels themselves carry a "prison" aura. People evolve, change, and so do their music. Some stuff will start as a particular genre, be branched into many subgenres, and then people will say "oh, it sounds like nothing we know, let's make up a new word".

The truth is, musical genres are useful to sort collections and to discover new music by browsing genres and subgenres neighbour to what you know, and that's about it. They should be as tags on the interwebs, dynamic, multiple, and ever-changing.

They are just vague indicators really, they can help sort things out and save time but shouldn't be adhered to as gospel. All music is just banging and pulling and stroking things at various volumes at the end of the day.