'I done it' shows a fairly sophisticated understanding of English in that the speaker 'knows' (subconsciously) that we generally use a past tense form if we wish to talk about an event in past time; The speaker also knows, though not formally perhaps, that the second (past-tense) form and the third (past participle) form are identical for over 98% of verbs in English.
It just happens that, for the majority of speakers of English today, the second and third forms of DO are different. This difference, and the use of the two forms 'did' and 'have done', are now accepted as standard English, and 'I done' is generally considered sub-standard.
There are still quite a few people who regularly use 'I done'. This may be for one of a number of reasons, including the acceptability of 'I done' in the speaker's own dialect or the deliberate rejection of what may be seen as authority or outdated middle-class standards.
We might say, perhaps, that 'I done' is not socio-culturally considered to be correct, but it is in some ways natural. However, while a minority of people might use 'I done' to talk about a past event, virtually everybody would reject 'I doing' for the same event. 'I doing' is not in any way natural.