Sure, but they showed her saying something to her dragon about going off to battle again, so it's not like this was her first rodeo...
Also, Rickon was just a child
I think this is more like when Jaime charged at Dany while she was standing next to Drogon...
That scene is an excellent parallel. What happened there is 100% completely in line with Jamie's character - he's got more balls than brains and so it makes complete sense that in the moment, with adrenaline pumping he would make that particular decision. (what was ridiculous was what followed next - him falling into the abyss and then somehow not drowning under 100 pounds of armour...but I digress).
I think there are two spheres of chracter mistakes; one worth complaining about and one that is essential to almost any story and thus is silly to complain about.
In the former category we have something where a character makes a decision or a series of decisions that is so out of line with their established character that it is just terrible writing. Daenerys in the last season of GOT is a good example of this.
On the other hand, we have the types of mistakes that are, to the viewer, silly, but are also human, and completely understandable and in line with the character's personality, and they help drive the plot. Ned Stark warning Cersei for example. Or in this case, Rhaenys going on her kamikaze mission (note the resignation in her face before she turns around) realizing that she had the chance to end the war then and there.