We live and perceive in the 3rd dimension. When you think of a hypothetical population of people living in the second dimension, you think "how naive that they can't see volume". They can only see vertical segments and are unaware of the beauty that is space. But we're in that same situation. We're stuck in a single point in time: the present. We like to think we exist in the future and the past, but we don't. We're always in the present, and we can't escape it. Time is always passing us by and it's difficult for us to realize it cause we're derivatives on the larger graph. Imagine a 4rth dimensional society that could experience time and live in the past and present. They would find it so trivial that we can only the present and can't experience all of time as once.
We think very one dimensionally. We think in terms of objectives and outcomes. When we realize the universe will eventually decay, we assume life is therefore meaningless. When we keep asking "why?", we eventually realize there isn't a clear "why?" for living, then we think life is meaningless.
1. I think it would be naive to assume life is meaningless because we can't grasp the reason for existence.
2. You can logically reason that life is meaningless, but if you're still scared to die you aren't embodying that belief.