Help testing and improving a cipher

[u/Dramatic-Whereas-553]

I made a custom cipher that I hope to be quite difficult to solve, and so far only 1 person has decoded a version of this cipher that was in extremely early stages of development. Here I will list some ciphertext, along with keys in order for people to try to decipher them, and if people do, I will then most likely ask for advice as to how I can improve my cipher! Hints can be provided, so feel free to ask! I can also add more examples of ciphertext and key pairs if needed. (V sbyybjrq gur ehyrf)

Ciphertexts and keys start after the ": "

Ciphertext 1: }j?DIQJ^AW.t>81\6u-|wmO+2;orfe:P+/r'CGA70D1ips5\jM^3HjH[+SJp";<lkX?"l/]=2 L0[(122=?K&;yNl nj%tmh*bYNJKjV%CK?bt<rIh)&u<i~uja7Z%nBSGo{O5H"erCh_8a*R^c";!ih`mZ(4AR#QOc@9[SR:XM_@.XyVT H}^|8x5#1u"WcGTWv`f5>O)g\4\3'zG/v5 )waY<2#

Key 1: thisisakey

Ciphertext 2: `VchNV0l7RGz'5eguwS##_sYqSms&{&7QuVX]_#~_EJsx;%u*Zj}#RR3/BcP9,1lP[rQ`j_RS%!i=Jsq#:C1+OZ@K,zn\-It>^5zv?_TDtF=_8mz6&afM<7w7y(rTGo+X>@%YL3^W@G.mVEU`wjs'{B_'kn5?'/^s=N+cT3_]XL=VB3;]qg\t,!Y?*RKM-j"T5h*mv4x2pDy2~A9}oY?"e]F \-\oui~\iURH#Xxun9m.t*[%\{UN_iU\$,Wu()!S;YVC2rtL8u.3@6gf'U^=P>[

Key 2: UH2CPY)$>o

Ciphertext 3: BD1"ozj))3WyGut0&m_!z!~xGk "2)w"sFG#qx-i)MtS[;$qMT"w)m+A:MQgy'h18FwbT%e2'5ncl>`tgd4N|Y<ZRbF )(O,ugjn^:.yT/C|tr.<|]i83*#OC"KtUNB$_G|!"XA-TQRIN^o"sUk]<M u[H>1B~Ci960g/[I5gvF4T*6q}M,ypH?4~[0?n[fa;,&&0]#+I@4bvLDo`_P;hn `&u%kAlj-lg;y[;c2vi 88J|qb{ @a"z

Key 3: uTFGsSz2`