I can’t speak to why all the states adopted a presidential system of government, but I can speak to why they are all the state legislatures are (mostly) bicameral. I worked as a research assistant in college studying malapportionment in legislatures.

Most states created their upper house legislatures to represent geographic regions of the state (typically counties or groups of counties). This created hugely malapportioned districts as the United States urbanized while rural districts maintained the same level of representation. The Supreme Court ultimately ruled in Reynolds v Sims that all state legislatures had to create districts that are roughly equal in population. This made the reason for having a separate upper and lower houses redundant, but most states have kept their bicameral legislatures.

However, Nebraska (the only state with a unicameral legislature) dissolved their bicameral legislature in 1934. Nebraska’s legislature was largely viewed as inefficient and wasteful which led the public to vote for its dissolution.

Edit: here’s a link to an earlier comment I made about bicameral state legislatures with sources https://www.reddit.com/r/AskHistorians/comments/aebvc0/why_did_the_crafters_of_the_various_us_state/edon94t/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

Many of the first 15 states originally did not have a senate, house of representatives, and a supreme court. For the most part, early state governments modeled themselves after Virginia and the House of Burgesses. The House of Burgesses, combined with a governer's council constituted a bicameral legislature called The General Assembly similiar to parliment with a upper house (governors council) and a lower house (House of Burgesses). By the time of the American Revolution, the 13 Colonies and Vermont had General Assemblies or Provincial Congresses with some differences in separation of powers and balance of powers. For Example New York's 1777 constitution provided for a very weak bicameral legislature with a governor that could dismiss it while Massachusetts's 1779 constitution provided for a strong, separated system of a house of representatives/ state senate, an executive branch, and a judiciary which became the model for the US constitution in 1789.

Interestingly, the first two states to be admitted to the union after the adoption of the Constitution reffered to their bodies as "Assemblies." Kentucky, admitted in 1791 opted to refer to its bicameral legislature as the general assembly. And Vermont, admitted in 1791, held a Unicameral General Assembly until 1836. Likewise Georgia and Pennsylvania held Unicameral assemblies until 1789 and 1791 respectively.

By the time Louisiana is admitted to the Union in 1812, all states except Vermont hold bicamerial legislatures, some being referred to as "Assemblies" still to this day but being composed of a house of representatives and a senate. Likewise most have an independent judiciary.

After this point, virtually every state admitted to the Union models its constitution and government after the US constitution and the Federal governement. The states that had not modeled their governments this way had been admitted before the adoption of the US Constitution in 1789 with the exception of Vermont. However, these states and Vermont fell in line over the course of the 19th century and amended their constitutions to be closer to the US Constitution or re-wrote them altogether.

Why you ask? At the end of the American Revolution, there was fierce debate and a myriad of ideas about how the former colonies would govern themselves. Most set-up a provisional congress similiar to the Continental Congress such as North Carolina and New York until they could draft their first constitution. These governments followed the general concept laid out by Virginia of a modified parlimentary system with separated powers. It was a system that had worked well for almost 200 years prior to the constitution and provided a good framework for the other states. Once the Constitution had been in place and the US government had been around for a couple of decades, they proved this Federal style of government was effective and there was little reason not to imitate it at the state level. This system made it easy to provide rural and urban representation throughout a state just as it equalized representation between populous and less-populos states at the national level. The three-branch system of legislation approved by an executive and scrutinized by a judiciary was an attactive method for creating state legislation and picking representatives for the national congress. An independent judiciary also provides a necessary practical arm of government to deal with state court proceedings which are far more numerous than federal court proceedings. Administrative judiciary procedures are handled at the state level, as well as the majority of criminal and civil cases.

Moreover, this "Presidential system" as you call it, is just a modified parlimentary system. A parlimentary system has a figurehead such as a King. States would have had trouble adopting a parlimentary system with no figurehead, as a prime minister lies within the legislative body. Thus there is no executive to "lead" an individual state. It would be like England having multiple parliments that had the national parliment over them. Sounds like a mess. So basically there was no precedent for anything other than what you call the presidental system. Bicameralism vs Unicameralism is sort if a separate question to Parlimentary vs Presidential. I think I answered that question adequately above explaining the representation between non-populous and populous areas being effectively governed by bicameral bodies.

In Summary: Proto-Presidential systems existed in the colonies long before the US Constitution was written. After it was adopted as the national government, it proved an effective system of government capable of fair representation through Bicameralism. As state after state joined the Union, there was little reason to adopt a different system as it worked well. States which had not modeled themselves after the system eventually amended or re-wrote their constitutions in order to do so.