The fundamental difference is this:
When the speaker has in mind (consciously or unconsciously) an ending time boundary for the state, action, event, etc, that the verb names or “is talking about”, or such a terminal end boundary for a time period in which such is anchored, the preterite (simple past tense) is used. The time period or periods may be implicit or explicit.
Something that ended and occurred in a time period that has ended at the time of utterance.
When the speaker has in mind that the state, action, event, etc, has no ending time boundary, or does not wish to convey it, or (sometimes) that the consequences or importance of the state, action, event, etc, the present perfect is used.
Something that occurred in the past but in a relevant time period whose termination is not marked.
It is complicated because we might conceptualize something in various ways, for example the meaning or sense of a word or phrase, or how the speaker is thinking about time intervals and how they interrelate.
If I want to convey that I was born, I will very likely say “I was born [+ (optionally) more]”, not “I have been ...” nor “I am” (though both of the latter are possible). The way that we think about the concept, the meaning of the word, is most responsible for this. The consequences of the event are enduring, and the event unsurprisingly remains important to me, but we nearly always think of birth as an event with an end: Once we’ve been evicted.
Someone would be likely to say “I have been baptized”, although if we imagine seeing a baptism in a movie, say, it may seem just as clearly an event with an end. Yet, it is often conceptualized differently: as an event which marks a lasting (perhaps eternal?) transformation.
If we reflect on how these two things are and can be similar, and question a bit deeply, we will find complexity. Is not birth also a transformation with important consequences?
Thus we gain insight into the fact that the human mind perceives and interprets a very complex and very mysterious world in ways that we often take as simple truths about reality.
(Much of this idea was discussed or alluded to in Ben Kibitz’ answer; I will return and see if I can improve on this answer.)
The linguist and scholar Noam Chomsky often says that modern science was born when Galileo and his contemporaries engaged in “a willingness to be puzzled by simple things”. It was once virtually universally obvious that the sun revolves around the earth. The classical Greeks, Aristotle, explained that steam rises and rocks fall to the ground “because things seek to go to their natural place”.
So it is today for most of us with human thought and language: Words do not “refer” to things in the real world. What we call “grammar rules” are not used by the mind-brain to comprehend and produce language. They are attempts to describe aspects of what we do when we externalize thought.
How we do that remains in large part mysterious and may forever be.
Consider: If we hear “a brown house”, how do we know that it’s brown on the exterior? This is not taught, yet 5 year olds know it.
What is a river? We “know”, yet there’s much we can’t explain. If we look away from a river and look back, its “essence” (perhaps) is gone. The water has flowed past and has been replaced. Yet it’s the same river. If it becomes 1% pollution, it’s still a river. 99%? Still. 100%? What if someone throws a teabag in it? Does it carry/contain water or tea?
Ideas from Chomsky. See for example, https://youtu.be/XNSxj0TVeJs. Search “Chomsky language” for many more. He uses somewhat high vocabulary and some of what he says requires some background to understand, but contrary to many, most I’d say, academics/intellectuals, his speech is clear; at least not deliberately designed to be obscure.
How to “learn” to use them? Don’t study them! Unless you find grammar to be a compelling area of inquiry for its own sake.
Just listen to and read things you can easily understand and that you truly enjoy. Attend to meaning, not form. Our brains use their own systems, abstract and unconscious, to build a mental representation of a language. We don’t know enough about how this works to “help” it. Humans were “designed”/evolved to acquire language and we cannot help but do it if we receive input that’s interesting and understandable.
Even the simple past is not simple.
Consider “You’re already going to class? I thought it started next week.” Is “started” the simple past tense there?
Bill VanPatten podcasts