Trouble redirecting all pages in a folder to a pag

I've searched, tried various examples, and none, other than creating an explicit list of redirect statements seems to work.
The biggest issue I have is that, although I have access to deploy web pages to the site, I do not have access to any web hosting control panel - site access was inherited, and until now it's been fine, but I think that it is either running an old version of apache, or rewrite rules are not allowed.
Anywa, over the years, the site has changed several times, and after registering the site with Google Webtools, I found the list of pages that gave crawl errors, so created an HTACCESS file to deal with these.
Over the years, there have been folders deployed and named in camel case and all lower case, and so all I wanted to do was to redirect all files in a folder to the new folder in the .htaccess file level, i.e.
My .HTACCESS currently has 120 lines, and an example batch are as follows:
redirect 301 /challenge/stanley_steamer.htm /lsr_history.html
redirect 301 /challenge/stanley_steamer.html /lsr_history.html
redirect 301 /Challenge/index.htm /lsr_history.html
redirect 301 /Challenge/Record.htm /lsr_history.html
redirect 301 /Challenge/Stanley_Steamer.htm /lsr_history.html
redirect 301 /Challenge/Sponsors/Avery_Weigh-Tronix.htm /sponsors.html
redirect 301 /contact/index.html /contact.html
redirect 301 /design/details.html /design.html
redirect 301 /design/index.html /design.html
redirect 301 /Design/Engine-drive_train.htm /design.html
redirect 301 /Design/Rear.htm /design.html
redirect 301 /Design/Home_Page.htm /design.html
redirect 301 /Design/index.htm /design.html
As you can see, I have some cases where the folder name is camel, others lower, and other cases where there is a htm and an html file of the same name that is listed in the crawl error log.
All I want to do is, in the example above, redirect all pages from /Challenge/ and /challenge/ to lsr_history.html, but all files in /Challenge/Sponsors/ to sponsors.html.
I also have a huge list of individual team pages that I list one by one and each one redirects to the new team page.
I've tried examples like:
RedirectMatch 301 ^/[Cc]hallenge/ /challenge.html, but this returns a 'Error 404 Not found'.
Any ideas or examples of how I can cut down my htaccess file to simplify this will be gratefully received.
Regards
Martin

I wouldn't bother searching for cases inside the match string for this kind of thing if I could avoid it - have you tried just specifying the RedirectMatch in lowercase, and appending [NC] to the end of every line? (that will tell mod_rewrite to ignore case and match regardless, which may save you some time)

if you have collections of similarly-formatted rewrites, why not group them together with one particular set of rules for each? That way you could cover, for example, all incoming URLs with one subdirectory with one rule, and all incoming URLs with a single subdirectory one with another rule. If nothing else, it could help simplify viewing the .htaccess file :)

(Take everything I suggest with a massive dose of salt, I'm still getting to grips with the black magick of mod_rewrite myself)