You say that you think it’s very possible that there was debris left behind from the life cycle of previous stars and planets, but have you ever really looked into or calculated the probability of one protein molecule forming from such debris or mineral like material. The probability of one single protein molecule randomly forming on its own is 2.02 in 10^321. This doesn't even touch the probability of thousands of these protein molecules forming into DNA strands; which turns out to be 1 in 10^40,000.
Setting aside the improbability of protein molecules and DNA strands forming on their own, the chance that our universe could/would be laid out the way it is, is extremely improbable. It's 1 in 10^133, to be exact.
The theory you laid out in your second paragraph was nicely done, but it’s only a theory. No one has ever seen this complete process take place. Why would we base our beliefs on the origin of life on a theory?
It doesn't seem like life is inevitable from the statistics above.
Peterson, Reichenbach, Hasker & Basinger (2007). Philosophy of Religion Selected Readings (Third Edition). Oxford university press, NY