It's not too difficult to connect one description to the other.

Cutting off the roots of Dukkha is the deep realization that there is no Dukkha to cut off and nothing to attain.

In a conventional sense, of course Samsara is bad and you are in it. But in an absolute sense the concepts of good and bad themselves don't exist - they are mental constructions, not things inherent to reality itself. The same goes for rebirth - in a very real sense the stuff of you-ness is continually unfolding and changing. There are some conventionally meaningful changes that we call "birth" and "death" (and within that framing, we cannot escape this and have countless rebirths) but even these are empty of inherent, non-mentally constructed meaning (hence: escape the cycle of birth and death by realizing what they really are: empty). They're important to "us" (the phenomena of self), our ego only, which is indeed a real phenomena, just not some kind of enduring spirit or essence. It is from the belief itself in the enduring reality and separateness of the self that our attachment, aversion, and suffering arises, when really we are one boundless system. One Brahman.

This is why we can say that karma ripens from the merit of past lives - it's not a point system, it's simply cause and effect of the whole. Samsara is the human condition that is simply that - a human condition.

This description is quite incomplete. Nirvana is not a metaphysical reality like heaven. Not-self is a mark of existence already, not something which is attained.

We have a fundamental intuition that we are a self that experiences time, space, birth, and death, as opposed to an inextricable and inseparable part of the unfolding of reality (including the phenomena which arise from those perceptions) not separate - this can be described in many ways including scientifically, but these are abstractions. Fundamental reality is not knowable because of what knowing is. Ignorance of this, along with aversion and grasping are the roots of all suffering, but are also empty of inherent nature. Nirvana is already here, we just don't realize it. The idea that Samsara is "bad" is one of the very ideas keeping you in Samsara.

It can be, yes, but only if you use it as an excuse to ignore common sense. I find it worthwhile to think about the fact that anything you are even remotely competent at began from a place of complete inexperience.

The advice is meant to counter the risky feeling of beginning something, not a critique of the importance of expertise.