tenía vs tuvo o ha tenido with an example?

Without context, each of the three sentences you provided are grammatically correct and possible. This is the kind of context I would supply or imagine:

1. Tuve un poco de tiempo para aprender español...
   ... ayer / la semana pasada / mientras estuve¹ en cuarentena.
   (that is, I had a little time and used it in the past; it's over now. If you don't say anything, one must suppose you did use your time to do what you said you had time for.)

¹ Where it says estuve you can substitute estaba; it doesn't change the meaning. However it sounds better (to me) if you use the same tense in both parts of the sentence.

2. Tenía un poco de tiempo para aprender español...
   ... el otro día / mientras estaba en cuarentena, pero no lo aproveché.
   (that is, for a while I had time; the sentence sounds incomplete, because the imperfect is used to set up a background context, so you'd better had something to add along the lines of "I had time... and I used it / but I didn't use it".)

3. He tenido un poco de tiempo para aprender español...
   ... y ahora siento que hablo mucho mejor el idioma.
   (that is, I've had time to study and this is the result; if you don't specify any result, it's understood that there was one, because this tense is preferred to talk about past actions that have enduring effects in the present.)

For general context (to paint the background picture, so to speak), use the imperfect. For specific events against that background, use the preterite. This is why "tuve tiempo para aprender" suggests you did learn, while "tenía tiempo para aprender" doesn't: the former says an event happened and finished; the latter only tells your audience something about the background, but doesn't advance the story.

P.S.: The simple preterite and the perfect (compound preterite), that is, #1 and #3, are very similar. In most of Spain and some parts of America (like the Andean highlands) a distinction is clearly made between them. In Spain, additionally, the compound tense is used a lot more even in situations where the simple tense should be (if the rules were strict). In other parts of America (mostly Argentina-Paraguay-Uruguay) the compound tense is used very rarely in common speech. In every case, of course, the speakers know and recognize both tenses, and the lost nuances of meaning are supplied by context.

Well, for 1 and 3, tehre's a simple rule of thumb:

• If the period of time is over, use the simple perfect.
• If the period of time is still occurring, or it's been today, then use the present perfect.

I mean: Tuve tiempo para aprender → yesterday, last week, last month, some years ago... anytime in which the period is over.

He tenido tiempo para aprender → today, this month, this summer, in my life... any period which has not finished yet.

This is not a strict rule but works quite well. However, take into account that many places just do not use the present perfect, such as Galicia and many countries in America. They jsut use "Tuve".

And... regarding "había", this is an imperfect tense. That means you can use it for actions that took some time in the past, and also routinesi n teh past.

Tenía tiempo para aprender can mean a routine (I used to have time to learn), or it can just mean "I had time to learn", but specifying that it was a long process, kind of "I was having time to learn".

In sum, the imperfect highlights the duration of the process, whereas the past simple is more suitable for "points in the timeline"