Nirvanic Inevitability

Recently I was perusing the internet in order to get some idea about what sort of misunderstandings of Buddhism are in circulation. It is, as American airmen during the first Iraq War used to say 'a target-rich environment.' And of course I'm just talking about the 'reasonable' stuff, the 'intelligent' but misinformed material. Putting it all together I got the impression that a good percentage of these misunderstanding are due to mistakenly attributing Hindu concepts to Buddhism. One such idea I found to be quite prevalent is what you could call the Doctrine of Nirvanic Inevitability. There seen to be two versions of this idea and they go like this. (1) Each time we die we are reborn into a gradually higher form (a germ, a cockroach, a frog, a mouse, a horse, a Republican, a Democratic, a Buddhist Democratic, a Buddhist monk, etc) until we eventually attain Enlightenment. The other version of this idea is that (2) we are here 'to learn.' Each time we are reborn we are given opportunities to learn about life and truth. As we learn we gradually move upwards until we…(fill in the gap) attain Nirvana/union with God/the Absolute/ see The Light, etc.
In a sense, this second version of the idea of Nirvanic Inevitability approaches the Buddha's Dhamma, but like the first version it includes or implies concepts that are not really Buddhist. (1) Both ideas suggest that Liberation or Realization is inevitable, and (2) both imply that there is some innate 'purpose' behind the process of birth and death
There is no hint of either of these ideas in the earliest record of the Buddha's teachings or even in the later versions (at least not that I know of. If anyone can correct me on this point please do - but it will be necessary to give chapter and verse). The only thing that comes near Nirvanic Inevitability is in the Tipitaka is the accounts of the teachings of Makkhali Gosala. He explained it by using the analogy of a ball of string, which, when thrown on the ground, continues to roll until it has completely unwound. 'Fool and wise alike go round and round until they (inevitably) put an end to suffering' (D.I,54). In early Medieval Hinduism the doctrine evolved that if you diligently adhere to your caste Dharma you will gradually be reborn into a higher caste until you are finally reborn as a brahman and from that position attain the goal - another version of the same idea. The Buddha's vision differed from all these ideas. There is, he implied, no 'purpose' or 'meaning' behind samsara; it is an impersonal and rather unpleasant process which 'just keeps rollin along', propelled by ignorance and craving. And until we reach what might be called the 'breakthrough point' or the 'critical mass', sotapati, there are no guarantees. We could go very high (one or another of the heaven realms) or very low. Further, the idea of a higher or lower rebirth in terms of caste, social or economic status, is nowhere suggested by the Buddha. In fact, he directly denied it. In the interesting he tells of an utterly poverty-strickened man who has a most advantageous rebirth (the implication is that he attained the sotapatianga) because he had faith, virtue, learning and wisdom. And in the Buddha's Dhamma there is no suggestion that we will just pick up these things as we go through life. They require an act of will, making an effort, trying.