The simplicity of that Lions Club card is really quite nice and highlights the stamp and postmark. Speaking of the latter, I don't remember every hearing it referred to as the "bicentenary" rather than "bicentennial" before. (I live quite near Centenary University, but I can't find info on how it got that name; it was founded about a decade before the first centennial.)
You made me look. Here's an explanation of the two words:https://www.merriam-webster.com/words-at-play/the-difference-between-centenary-and-centennial-usage-history
Wow. That first postcard must be pretty old. When was the last time you could send one for 1¢?
Postcard rates went to 2 cents at the beginning of 1952. I saw a postmarked copy of that particular card from 1941 so the design is at least 80 years old. Though I do have a lot of cards from the so called "linen" era I prefer those from 1900-1929.