Quran is timeless, sound and complete?

First of all I wanna say that this is a discussion. I have been thinking about this and I haven’t even arrived at a conclusion of my own. So I figured that holding a discussion here might enlighten me about other opinions that I didn’t think of.

The Quran is said to be timeless, sound and complete. So by timeless, it is meant (correct me if I am wrong) that no matter the day and age it will be correct. By complete it means (correct me if I am wrong) that it includes everything that we need to know, that it has everything that god wanted to tell us. By sound it means (correct me if I am wrong) that it makes sense and is always correct.

1) So if it is complete then why do we need hadiths? The Quran is enough? And if we need the hadiths this will contradict that the Quran is complete and will imply that it is missing things and if it is then why did god make mohamed sws live longer to continue giving him the rest of it? And if the rest of it was the hadiths then why aren’t they mentioned in the Quran? Like follow the hadiths?

2) If its sound and timeless then why do we need people who must study islam for a long time to fully understand the Quran? If the Quran is the word of god and it is the guidance that everyone needs then shouldn’t it be easy to read and understand? God is capable of doing anything so why didn’t he make the Quran easy for everyone? And if some people who misunderstood the Quran, for example, terrorists. Then isn’t this on God? He knows everything. So god knew that Quran written in this was will be misunderstood so why do it this way? If something is so important it should be easy to interpret.

Some people will say its like laws and lawyers spend years studying etc. but law is man made. Quran is not. And if it was misunderstood and people nowadays are leaving islam or doing terrible things in the name of islam. Then they shouldn’t be punished by God. Because its Gods fault that the Quran wasn’t well written.

What do you think?