The moment you claim something "is" something, you have made a claim to some truth. You said they were aliens or god. The fact is they can be claimed as nothing better than figments of your imagination until you can bring something objectively meaningful back from your trip. I don't take issue with the fact that you thought you saw god, aliens, or Elvis. I do take issue with your unsubstantiated claim that it has any objective meaning beyond shared responses like any drug has; that is the claim made by you when you say it's aliens or god.
I would imagine this man would disagree...
Terrance McKenna and DMT
The molecule DMT (N,N-Dimethyltryptamine) is a psychoactive chemical that causes intense visions and can induce its users to quickly enter a completely different "environment" that some have likened to an alien or parallel universe. The transition from our world to theirs occurs with no cessation of consciousness or quality of awareness. In this environment, beings often appear who interact with the person who is using DMT. The beings appear to inhabit this parallel realm. The DMT experience has the feel of reality in terms of detail and potential for exploration. The creatures encountered are often identified as being alienlike or elflike. Some of the creatures appear to be three-dimensional. Others appear to lack depth.
Author Terence McKenna has used DMT and feels that, "Right here and now, one quanta away, there is raging a universe of active intelligence that is transhuman, hyperdimensional, and extremely alien... What is driving religious feeling today is a wish for contact with this other universe." The aliens seen while using DMT present themselves "with information that is not drawn from the personal history of the individual."
DMT is also naturally produced in small quantities in the human brain, and it has been hypothesized that DMT is produced in the pineal gland in the brain. The pineal gland appears in the developing human fetus around 49 days after conception. Perhaps an embryo should not be considered human until DMT production commences. Note that "zygotic personhood" (the idea that a fertilized egg is a person) is a recent concept. For example, before 1869, the Catholic church believed that the embryo was not a person until it was 40 days old. Naturally occurring DMT may play a role in near-death experiences and alien-abduction experiences.
Is it possible that the reality exposed to humans by injecting DMT is in some sense a valid reality, on par with our normal reality? Our minds, which evolved to help us run from lions on the African savannas, might not be engineered to see these other realities under normal circumstances.
What is the guarantee that our minds are naturally designed to sense the "true reality"? Perhaps there is no guarantee. If this concept seems weird, consider a far-fetched example. Imagine a creature or phenomena that has been lurking among us since the dawn of evolution. If our ancient ancestors died every time they perceived the phenomena, evolution would favor creatures who did not perceive the creatures or phenomena. One might counter this argument by saying that our modern instruments, such as X-ray machines and cameras, should be able to make the creatures apparent to us, even if our unaided sensorium is not up to the task. Reasoning further, because our instruments have not made these realms apparent to us, the realms must not be real. However, perhaps our traditional instruments and theories are also not up to the task. Or perhaps our interpretation of the instruments' results is incomplete. Perhaps DMT is an instrument.
As a metaphor, consider infrared goggles. A person leans on a tree. At night, we don't see the person. Put the goggles on, and a new reality results — a truer reality — and we see the man. Similarly, is it possible that our brain is a filter, and the use of DMT is like slipping on infrared goggles, allowing us to perceive a valid reality that is inches away and all around us?