Oct 13, 2021 - 07:27 AM
There are several past tenses in German, as there are several past tenses in English too, or most languages actually..and there isn't really one tense more common than the other since they're used in different cases.
The tense with the auxiliary "haben" + past participle of the verb ("ich habe gesehen") is called "Perfekt" and mostly corresponds to the English present perfect (have + past participle as in I have seen, I have come...). In this tense it's true that some verbs don't use the auxiliary "haben" but "sein" as in "ich bin gekommen", so you have to learn them individually.
And the other past tense with a specific conjugation ("sah" or "kam" for example) is called "Präteritum" and mostly corresponds to the English preterit or simple past (I saw, I came...)
Hope it helps clarifying things a little, keep it up!