George Carlin had a theory and I can't find any noteworthy flaws in it. [1] Our entire purpose could be to make plastic.
However, We experience "Objective Reality" through our Subjective Senses and infer/deduce more in our "Mind" from experiences/memories/recorded knowledge/etc. using various methodologies/tools.
Based on the above, we build "Worldviews" expressed as "Philosophies" and practiced as "Religions". It is in this domain that your questions make sense and answers can be given. A materialistic/utilitarian philosophy will give you a different answer from an idealistic one.
Note that though objective reality exists (since it is common to others besides oneself) it is through our observations/perceptions/deductions of it through our senses (and extensions of it via technology) that the mind defines/accepts a worldview model. A good way to think about it is as a blank canvas (i.e. nihilism) on which you paint your chosen philosophies.
It is for this reason that ancient Hindu/Buddhist/Greek/etc. philosophies placed "The Mind" at the center of existence and framed "Reality as an Illusion" i.e. your perceived/deduced reality actually exists on a more fundamental substrate. An example often used is that of waves on water where water is the reality and waves are the illusion since they come and go.
Hindu/Buddhist philosophies go further by disambiguating "The Mind" (the field in which emotions/feelings/experiences/thoughts/memories operate) from "Consciousness" (pure awareness which witnesses the above). Based on these theories they define a "universal framework" (viz. goals, stages and duty in life) for all of mankind. Here is a previous comment of mine explaining it - https://news.ycombinator.com/item?id=48325659
Some resources for further study;
1) Philosophy in a Meaningless Life: A System of Nihilism, Consciousness and Reality by James Tartaglia (free ebook) - https://www.bloomsburycollections.com/monograph?docid=b-9781...
2) In Hinduism, the different philosophical schools are called "Darsanas" which literally means a mode of seeing reality i.e. a worldview. There are six major schools and lots of minor ones. A good introduction can be found in An Introduction to Indian Philosophy by Satischandra Chatterjee and Dhirendramohan Datta. Pdf at - https://archive.org/download/IntroductionToIndianPhilosophy/...