If you are new to Spanish, you shouldn't be troubling yourself to understand what you think to be anomalies. Each of those words/phrases has it's own purpose in the language, it's not like you just pick one and use it.
Yes, they all mean from
. But even in English, there are different variations of from
.
Since, Starting at, Originating, Deriving, Materializing, Dematerializing
Desde
is used to introduce, indicate and designate a starting point in your sentence, and always in the past.
Desde el día que llegué aquí comía muchos legumbres.
Since the day I arrived here I ate a lot of vegetables.
Mi padre me dió una cerveza cuándo era niño y desde entonces yo era alcohólico.
My dad gave me a beer when I was a child and since then I have been an alcoholic.
A partir de
does the same thing but it's more flexible. This preposition allow you to set your starting point in the future.
A partir de la próxima semana empezaré a hacer ejercicio.
Starting next week I will start exercising.
A partir de que llegue Pablo prepararé la cena.
As soon as Pablo arrives, I will prepare dinner.
Se explotará una burbuja a partir de que se la toque.
A bubble will explode as soon as it is touched.