The only other tenses commonly used are the conditional/future and their meaning is approximately the same of the present/preterit imperfect described herein.
en.wikipedia.org The present singular is formed from the original singular preterite stem and the present plural from the original plural preterite stem.
en.wikipedia.org Conjugation includes three persons, two numbers (singular and plural), three moods (indicative, imperative and subjunctive), and two tenses (present and preterite).
en.wikipedia.org These were originally aspectual, but developed into something more like a preterite and future.
en.wikipedia.org Six morphological forms for tenses, aspects, and/or moods present, preterite, imperfect, pluperfect, future, and conditional.: 6.
en.wikipedia.org