Human intelligence is not capable of understanding the universe in a complete way.
We lack the hardware: we have the sense of touch, smell, taste, sight, and hearing, all are rather specifically tuned to our most proximate use cases, maybe we have a few more senses that we haven't articulated well yet, but probably not very useful (in a grand sense).
We lack the software: While we are intelligent relative to every other form of life on Earth (that we know about), it seems highly unlikely that we are just now in the place and time in the existence of our species that we have developed the level of consciousness and insight and (contemporaneously) the scientific understanding and material knowledge and capabilities required to characterize the reality we live in.
An amoeba cannot imagine the intellect of a frog, and the frog cannot imagine the intellect of a human being, and so-on. There is no reason to think we are not rather low on the chain of possible animal intelligence. There may be hard limits on the level of intelligence that can be obtained via natural selection of carbon based life-forms on our planet, and even if we could become dramatically more intelligent (IQ 300, 3000, 30000, etc.) it is unclear (and improbable) that the combination of our evolved sensory mechanisms (hardware for obtaining information) and intelligence (software) would be "the right stuff" to discover the essence of existence...because evolution is more about keeping score of who gets laid, and there is no reason to think that the "understand the universe and all of material reality" sidequest has any correlation with getting laid. You could reasonably say that, for example, biomass is a form of embodied wisdom - "There is a lot of us and we aren't going anywhere," then plants, protists, fungi, bacteria, etc. all seem to have us beat. While it seems highly likely that 1 million years from now there will be trees that strongly resemble those that exist now, it is highly unlikely that humans in our ultra complicated ultra niche fragile life cycle will exist in our current form. Hard to say probability-wise if we will continue to increase in our complexity (sensory abilities, consciousness, intellect), because there is an intuitive sense that simplicity a la ants is a better strategy, yet we do exist...