Extraordinary claim, to put it lightly.

**It's probably impossible to ever claim something is spiritual and know it fully _to be_. (There are just too many options for what spiritual might even be, and evidence would always be hard to come by.) However, in a few different ways that we commonly think of spirituality, I would say humans do possess something that we could call a spiritual dimension.** - We engage in general feelings of there being something greater than ourselves, even if we don't directly connect those feelings to something like a specific higher power or a non-material level of existence. An (albeit contested) example of this is art: We often say that the arts touch something "other than our emotions and reasoning." It's not uncommon to consider art as satisfying some spiritual side to us rather than only our emotional and reasoning sides. (Or even as satisfying the last of another common set of qualities: Mind, body, "soul.") - Even if we don't believe we are, for example, praying to a higher power, a lot of people do engage in wishful thinking, perhaps without being aware of it. For true skeptics, the philosophical hardline is actually that everything beyond your current moment and sense of self right now is faith. You have faith when you believe in anything beyond Descartes's famous feeling of: "I think, therefore I am." Now, whether that's to be equated with spirituality is another question altogether, but I could envision a line of reasoning where we do just that. - The art and practice of meditation, although certainly not common to everyone, is popular enough that we could consider it a kind of entering into some sort of potentially spiritual state of existence when done in a certain way. The loss of ego that comes with some forms of meditation is a loss that does, indeed, seem to see "us" engaging with general feelings and notions of there being something "greater than us". - There are probably tons more examples besides these, and of course, the above could always fairly easily be considered non-spiritual, so I'm mixed.