When we refer to past lives, future lives, parallel lives, etc., are we ever in the same physical form, albeit perhaps of a different age, as we are in our ‘current’ life, or are we likely a different physical form or entity compared to what we are in our ‘current’ life?

Within each lifetime, you are the species of being you are choosing to inhabit during the incarnation. It is always physically different than your current self because being in a different time and place with a differing genetic composition and ancestry coming together to form a new physical body, there will be many differences. The idea of people reincarnating to be a look-alike is a primitive human perspective based on the expectation that someone will come back as themselves, including physical appearance, but this is not the case. If there is a reincarnation within the same family grouping, there may well be a physical resemblance by virtue of that ancestral gene pool that will be a factor governing the morphology of the form and appearance of a child born to a member of that same lineage, but that is a weak link and simply a minor detail. What truly matters for the incarnation is the work done by the soul with the new life opportunity, and this will take place within the hand that has been dealt for that life—the grouping in the family, the makeup of the person’s physical body and appearance, their ability to use the brain of that physical body to express intelligence and high level functioning, and so forth. In the same way beauty is only skin deep, the physical container one inhabits during an incarnation is only a surface representation of the soul being projected into the earth plane at the moment. The invisible, intangible, energetic life force and its inner workings and interactions with various planes of existence are a much more profound influence on things than the physical body itself.