What are the benefits of Dhamma in this very life that could be understood by a beginner?

"Beginners" should be taught what is honest & true (rather than speculations & superstitions).

For example, the Maha-Mangala Sutta lists the many blessings of the Buddha-Dhamma, without mentioning 're-birth' or 're-incarnation'.

Following the guidance given in the Pali scriptures, beginners can be taught the following dependent upon their needs & aspirations:

(1) The many benefits of morality (non-harming), which include the preservation of psychological 'normalcy', integrity, self-respect, trustworthiness, social relationships & freedom from remorse & regret.

(2) The benefits of giving/generosity, which include happiness, beauty, strength & self-respect.

(3) The dangers of sensuality & extreme behaviours (such as gambling, intoxicants, etc), which include addiction, loss of freedom, breakdown of relationships, loss of wealth, bad health, etc.

(4) The benefits of the Brahmavihara, here.

(5) The benefits of concentration meditation, particularly how it brings a free here-&-now pleasure/happiness that is superior to worldly/sensual happiness.

(6) The benefits of wisdom, in ending sorrow & suffering & guiding life safely.

The Blessed One discoursed to him a graduated sermon, that is to say, he spoke on the subjects of liberality, virtue, the heavens, on the evil consequences, the vanity and the depravity of sensual pleasures, and on the advantages of renunciation.

When the Blessed One perceived that the mind of Upāli, the householder, was prepared, pliant, free from obstacles, elevated and lucid, then he revealed to him that exalted doctrine of the Buddhas, viz. Suffering, its Cause, its Ceasing and the Path.

Upali Sutta

The immediate benefits of Dharma are many many, depends on how the student gets it. As a personal experience, from someone who almost "despised" when learnt the "world religions, Buddhism" on primary school history lession formed a negative perception, to a particular occasion tasted the authentic favour of the Dharma:

1. You will understand how the world is formed and why everything exists, literally speaking.
2. You will realize that confrontation is useless, war will not end war, protest will not bring equality... you will be much wiser in dealing with matters.
3. You will know that humans are limitless, instead the body and mind is the cell to block our knowing.
4. We are the master of our destiny. What we sow is what we reap, therefore, we could be in peace with ourselves and what we do and what happen, no one to blame, no unfairness, in fact; in the long test by time.
5. There is a perfect stage that can be reached by mere human, not by any salvation, by any mercy of a god. This perfectness is all knowing and in bliss.
6. You will naturally start to treasure and respect all living beings, including plants, insects, animals... because they have the same essence in you, and you somehow involved in creating them, literally speaking.
7. You will become more intelligent, and with better temperament.
8. Your appearance will become more lovely, people will become more friendly to you and like to be around you.
9. You will not be driven by the hectic and noisiness of the now-a-day life pace, for you have found the center/pillar, instead of drifting like a log in the sea.
10. You will not fear death as if you fear darkness in an bottomless abyss or endless night; but you will fear death because the rotting of the body after death (my current stage, especially seeing the photos of the Sky Burial).

There are many many more...

1. Karma works in this life too. If you are kind to people, you create friends, then friends will take care of you. This is called karma - creating conditions for your future, in this life.

2. When you are driven by emotions, like obsession or negativity - you become kind of blind, so you create bad conditions for yourself. So seeing your mind and developing ability to stop harmful thoughts is useful for you, in this life.

3. Stupid people always argue about things, they always see them from one side only. Buddhism teaches you that things have many sides, and when you see it from all sides - you don't argue. This is useful for you, in this life.