English tends to keep words in the spelling of the language they were borrowed from, or something close to it. The -able and -ible endings are often on words of Latin origin. The endings -ant and -ent are another source of spelling confusion. Sometimes it helps if you've had Latin and can remember which conjugation the Latin verb belongs to that the English word is derived from (to know how to spell the English word).
It would theoretically be possible to change to a completely phonetic system for English (by creating additional characters) but that would be far too much trouble for most people who already know how to read English.
Theodore Roosevelt believed in simplified spelling and had a list of revised spellings he wanted everyone to adopt...and got nowhere with it.
A totally phonetic English spelling system would, by some accounts I've read, require anywhere from 89 to over 120 different characters.
That's to accommodate everybody but the guys in Jamaica, eh!