Differing ser from estar is a tough issue in Spanish. It needs some practice but there are a few main rules. Estar is either used for describing the physical placement of someone or something (Lucía está en la calle Cervantes; los libros de Miguel están en su habitación) or to give a clue about how the person looks like, feels like etc at a precise moment (Estoy cansadísima esta tarde; ¿por qué está tan colorada Angela?). When the person or object is normally this way, it´s their common feature, we use ser (Dolores es normalmente muy pálida pero hoy está colorada; mi carro es mercedes, es grande y rojo; soy polaca) It´s a long and tricky topic, I´m pretty sure you´ll find a complete explanation in your language.

i think estoy is used when it's something temporary

I'm pretty new but this seems to be a common topic. It seems a simplified way to explain it is Estar is used more for something temporary or happening now. Ser is used with more permanence. So Estoy Cansado - I am (right now) tired. Soy Consado would be more that you are always tired or you are a tired person. of course there is gray area, but that seems to be the explanation to get started. So Estoy aborrido means I am bored. Soy aborrido means I am boring. At least that is my understanding so far.

i'm tired = Estoy cansado i am tired = Yo soy cansado

you use the verb ''estoy'' when you feel tired because you are not tired is how to say I am an engineer( you study for this) not born whith this. The explication in spanich is: Usas el verbo ''estoy'' para decir que tienes ese estado de animo, prabablemente por trabajar y utilizas ''soy'' cuando quieres decir que naciste con ello o conseguiste eso, por ejemplo al decir ''soy hombre(naces así)'' o al decir ''soy ingeniero(conseguiste esto por estudiar)'' Espero haberte ayudado ;)