We use Past Simple to describe states in the past:
I knew how to swim at the age of 5
She looked beautiful at the party
I felt cold
They were tired after work
Difference between Present Perfect and Past Simple regarding states / stative verbs
We use Present Perfect if a state started some time ago and continues until the moment of speaking the sentence. (see Present Perfect: Actions started in the past and continuing in the present). We also use it to express the fact of recent events:
There’s been no sign of Malaysia Airlines Flight 370 since it disappeared. The families of the missing have been angry with Malaysia’s government. They say it’s been slow to release information.
An interesting example. We can notice that we are using the present tense when translating it into another language. The present perfect tense in English (Present Perfect), in this example, shows us that the state began in the past and continues to the present. Therefore, we translate this state into another language using the verb in the present tense.
If we want to show the state continues until now or stress the fact of state, we use Present Perfect:
I‘ve been happy all my life
If we want to show that some state was there at some point in the past, we use Past Simple:
I was happy (because I earned 12 dollars)
Also on Past Simple: