SPOILERS!!!!! Stop looking at this series as a literal interpretation of man vs. alien. It is more like yin vs. yang! Stop assuming no questions were answered. It is a metaphorical journey into a person's psyche.
Part one deals with a kid experiencing the loss of loved ones (either his brother or his parents, or both, depending on what dream reality you are following). Reggie experienced that loss too.
In life we all face our mortality, suffer through fears, and our own human ego / Satan chattering it up with negativity in our heads. As an ongoing battle for enlightenment within your own mind the Phantasm series puts an entertaining experience to that representation. "It's all in your head".
If you are confused and complaining about Ravager you are missing the point. The series hit on action, goof ball slap stick comedy, horror, metaphysical and multi-dimensional layers, and vibrations (which is what forms the Universe). The tuning forks is the visual representation... ie: control your vibration and you prevent fear from taking control of your life. Control your mind away from playing tricks on you by inventing up negative stories that are not even true, you find happiness.
In Oblivion, Mike found peace in the desert scene after blowing up The Tall Man. He had resisted all his life up to this point and when he finally killed The Tall Man, another one steps out of the dimensional gate, totally deflating any form of celebration. However, this is exactly what was needed... Mike let go... gave up fighting fear and death (The Tall Man is symbolic of those) and that's when IT took the sphere out of Mike's head and left. Mike won. He found peace and no longer was it all eating away at him inside. This is shown by the camera entering his "single eye", it morphing into an eye that is letting a lot of light in by shrinking his pupil, and showing him as a kid with Reggie. Reggie hears negativity... "I'm dying"... while Mike, finally at peace, says "it's only the wind". The fitting ending... to his story. He found his way out of Limbo.
Bible Quote... Matthew 6:22 "The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light." The spheres attack your third eye... they drill into them. Those who cannot see within... aka... are not in alignment with truth and Spirit, die inside. Their 3rd eye is blocked and they are stuck in the 3rd dimension of the material and death.
Ravager is Reggie's story because at the end of Oblivion he kept fighting... by running into the dimensional gateway after the new Tall Man. He didn't find peace. Ravager is the outcome of that choice... a man facing dementia trying to find peace but still fighting it through the alternative reality of what ever happened when he went running through the gate in the desert.
There are two endings in Ravager during the end credits. 1... Reggie dies old surrounded by his friends. The other, he remains in a never ending battle with the Tall Man while still wearing the ice cream man uniform from Oblivion. His peace was from being reunited with his friends, which "The Trio" is all he ever wanted to be happy. Both possible realities play out... and it is up to us, as viewers, to accept that all choices are possible depending on how we decide to live our lives. Do you accept fear and hide from it or do you face it, find peace with it, and go live your dreams in peace? For Reggie, facing it means fighting on in one dimension, side-by-side with his buddies, or by letting go and dying surrounded by loved ones in the other because too much time had passed.
I love the Phantasm series because I get it... I get the theme, the metaphors, and the Tall Man, for he is watching us all. What / who will you be on your death bed? What regrets will you have? Thank you Phantasm!