What factors create change?

For this discussion board, we are going to examine the idea of the
historical thinking skill of causality. Historians consider causality because
it allows us to make hypotheses about what factors create change, war,
political upheaval, revolutions, etc. Read the formal definition here.

historicalthinking.ca/cause-and-consequence

You can also watch this video:

youtube.com/watch?v=LJpakulluOY&t=2s

For your initial post: you will consider the fall of the Western Roman Empire (476 CE). What do you believe what the strongest factor that caused its downfall? While the fall of Rome had many factors, you are
limited to discussing, at most, 2 interrelated factors.