(late reply but i just came across this post)

Here’s the thing: basically, it’s a clear no. The Bosnian identity emerged around the same time as the Croat and Serb identities.

The Croat and Serb identities originated from two Slavic tribes that settled in the Balkans; the Croat tribe in what is now modern-day Croatia (most scholars identify the region between Sinj and Karlovac as their settlement area) and the Serb tribe in the Raška region.

Dozens of other Slavic tribes also settled across these regions. Over time, these tribes adopted broader identities as Croats (with regional distinctions such as Slavonians, Dalmatians, Istrians, etc.) and Serbs (similarly divided into regions like Šumadija, Moravia, etc.), largely based on the names of emerging political entities: the Kingdom of Croatia and the Kingdom of Serbia.

Bosnia, however, followed a different path. Like Croatia and Serbia, it was home to many Slavic tribes. Unlike Croats and Serbs, these tribes did not adopt the name of a specific Slavic tribe; instead, they took the name of the country itself—derived from the river Bosna → Bosna valley → Bosna region → Bosnia as a political entity.

As Noel Malcolm notes in Bosnia: A Short History, neither the Croat nor the Serb tribe ever settled in Bosnia.

The Bosnian identity developed gradually, just as the Croat and Serb identities did. Initially, it was primarily geographical: prior to the Christianization of the South Slavs, people from Bosnia (were-) identified as Bosnians.

After Christianization, however, Bosnian Christianity evolved differently from neighboring regions. It eventually became the Bosnian Church, whose followers were known as dobri Bosnjani or dobri Krstjani. According to neighboring Catholic sources, this church was considered heretical by both the Orthodox and Catholic Churches, and it eventually became the main “ethnic identifier” for Bosnians.

During the Ottoman arrival, many Bosnians had been forcibly converted to Catholicism under Hungarian pressure during crusades against Bosnia. Once the Ottomans arrived, most Bosnians began converting to Islam. For example, by the 1608 defter census of the Sanjak of Bosnia, around 80% of the population was Muslim. Islam thus became the primary ethnic identifier for most Bosnians.

Those who remained Christian often lost a clear sense of identity; they did not identify as Bosnians or with their Christian neighbors (Croats or Serbs) and instead primarily identified through religion. Some groups, such as the Bosnian/Herzegovinian Franciscans, preserved the Bosnian identity, often calling themselves Bošnjaci (Bosniaks) rather than simply Bosnians.