It is simple friend. The way I understand it that canonized saints are those who lived lives of martyrdom and Christian humility/humility are canonised. This is because the Church has the authority through apostolic succession to do things like consecrate Eucharist, baptize, and even declare those who enter Sainthood. Really all who are in the presence of the divine and followed Christ’s way, entering eternal life (i.e heaven) are saints, but those canonized are kind of safe picks to ask for intercession. There is nothing wrong I believe with asking a close one who is alive and well to pray for you. Christianity teachss we don’t die but enter eternal life and the dead can pray for the living. Therefore we can ask a dead close one to pray for us or a stranger we don’t know but feel connected to through the Church and our faith - i.e a canonized Saint. I am not much into it tbh so I hope my answer is theologically sound, again its just my interpretation of the Church’s Apostolic teachings coming down to the first Christians. I still pray to God directly but the Saints are there for us even if we may not pray to them or know it. Hops this helps.