Ottomans were not Arab by any-means. Ottoman State is founded by Osman Bey, leader of the Kayi Tribe which is a sub-tribe of Oghuz Turks, who migrated from Khorasan. The official language in Ottoman empire was Ottoman Turkish, which is basically Turkish with many many Persian and Arabic words, while the structure and grammer was Turkish. Ottoman Turkish mainly used in Istanbul by a limited-number of people who are closed to state affairs or some educated people like poets or government officials in the federal states. Common people was speaking plan Turkish, which don't have much Persian and Arabic influence, and this language was the language of the Ottoman Army. Ottoman state and army culture, discipline and structure was a classical Turkish state structure, of course with differences from previous Turkish states.

The problem Arabs faced after dissolution of Ottoman Empire is similar in a sense to Turkish people faced, in regards to the national awareness.

Ottoman Empire didn't dissolved because they chose the wrong side, instead it was huge empire consisting of many nation and spans over an enourmous area (East Europe, Anatolia, Syria-Iraq, Egypt, Arabia, North Africa), while the army and many government offices couldn't keep up with the developments of the time. Basically, Ottoman Empire dissolved because of the wrong politics and failure to renew itself. After the French Revolution, nationalism started to spread over whole Europe and this affected the Ottoman Empire most, not only consisting of different nations, but also different religions. Being a religious state (Islamic), main subjects were Muslims and non-Muslims, separated by Millet system according to religious affiliation. Government officials were either Turkish or Devshirmes (Christian boys converted to Islam and trained to be gov. officials), being Muslim even wasn't a qualification to be an official.

When nationalism sweeps Europe, Christian Balkan nations like Greeks, Serbians, Bulgars etc. started to rebel against the empire to found their own independent nation states, feeling comfortable as the empire was loosing power every day. In that situation, Ottoman government was trying to cope with "the problem" by supporting the empire-identity of Ottomanism, and only small number of educated people were following the idea of Turkish nationalism and to create a Turkish nation-state. This was all happening at the last decades of 1800s, and Ottomans lost Balkan region, latery Ottomans also lost Middle East, Egypt, Iraq, Arabia, North Africa. British Empire also supported Arab nations to rebel against Ottoman Empire, promising their own land (British Mandates).

Empire was already dissolved when most of the nations declared their independence. WW1 was just nail in the coffin, that officially surrendered Ottoman Empire and Istanbul to British Empire. After the end of WW2, Allied forces (British, Greek, French, Italian, Armenian) shared the remnants of the empire with Treaty of Sevres, but Ottoman Army generals and irregular Turkish armed forces rebelled against the invading forces and this resulted in the victory for the Turkish side in the War of Independence, and ultimately resulted in the foundation of the Turkish national state.

TL;DR: Empire didn't dissolved because of choosing the German side. And also Arab nations didn't share "ottoman" ideals as Turkish and even many non-Muslim millet did and finally rebelled against Ottomans with the British support. Saying Ottoman Empire was an Arab Empire is simply ignoring the historical facts. This is not so different than saying all the Christian nations in Europe are descending of the Jews because Jesus was one. Having words from a language and having the same religious affiliation doesn't make two different states, nations or cultures one.

https://en.wikipedia.org/wiki/Decline_and_modernization_of_t...
https://en.wikipedia.org/wiki/Rise_of_nationalism_in_the_Ott...
https://en.wikipedia.org/wiki/Turkish_War_of_Independence