Hello @Souna - welcome to our community.
I did a little bit of research about this topic.
The reason why there is few refugees coming to Europe by plane is that airlines take a risk by letting them on their planes. In accordance with EU Council Directive 2001/51/EG they have to pay for accommodation, catering, the return trip and a fee in case they bring someone here without a visa that doesn’t get asylum. Technically they have to check at the counter before check-in if you are entitled to get a refugee status in your target country. But in reality that’s impossible for them to figure on the spot which is why they won’t let anyone without a valid visa on the plane.
Sources (German language):
As you said you usually don’t need a visa if you stay in the transit area of an airport and travel to another foreign country afterwards. But there are exceptions from this rule: citizens from Lebanon (amongst other countries) need an airport transit visa even if they are not leaving the transit zone.
So without a valid airport transit visa the airline probably won’t let you enter their planes. In order to obtain such a visa you have to go to the German embassy in Beirut. You have to use this website to book an appointment: